Electric aircraft: NASA tests a new approach

LEAPTechAt the last salon du Bourget, Airbus presented its E-Fan, light aircraft powered by two Kort driven by 2 motors with a power of 60 kW. NASA also funds research projects on electric propulsion of aircraft light. The LEAPTech project contrasts with the usual aircraft configurations. This 4-seater aircraft has not less than 20 motors and as many propellers. Better, these propellers are folding when the phase of flight does not require full power. This is what NASA calls the distributed electric propulsion.

Multiple motors to blow on the wing

CFD Simulation from the flow of the stream of the propellers on the profile of the wing.

CFD Simulation from the flow of the stream of the propellers on the profile of the wing.

How not to think these multirotors drones where designers multiply the propellers and electric motors to increase the burden of their devices. With its LEAPTech approach, NASA tests the concept on an fixed wing aircraft. For now, his wing equipped with engines Vingts is being tested on a truck after having passed the test of the blower.

This mode of propulsion, if it keeps its present promises multiple benefits. In addition to the low impact of a failure engine on flight, dispose of the propellers of small size on the length of the wing allows increase the pressure of the air on the wing at low speed. Engineers can must design a wing optimized for cruise flight. Joby Aviation is working on the prototype of the LEAPTech on behalf of NASA. It is made on the basis of the small twin-engine Tecnam P2006T. The LEAPTech will be a comparable to the Cirrus four ‘traditional’ SR22 will weigh 3,000 pounds against 3.4000 for the SR22 and its wing area will be that of 5.1 m2 against 13.5 m2 for the classic single-engine. Only concession on its rival, the slightly lower top speed. Regarding autonomy, the LEAPTech will be able to fly on 370 km in 100% electric and 740 km in hybrid mode.

Joby S2

Le concept S2 de Joby Aviation.

In addition, researchers are working on propellers with broad blades turning at low speed, thus less noisy than traditional propellers. They are foldable and come to drown in the pods when the corresponding electric motors are stopped. NASA and Joby Aviation ambition does not stop at this light aircraft. A two-seater convertible half & S2 is already in the cards. In a year or two, it might attempt to take to the air thanks to its… 16 propellers.

 
Translation : Bing Translator
 

Sources :

“The Next Big Thing”, Flying, December 30, 2014

“NASA Plans Tests Of Distributed Electric Propulsion”, AviationWeek, July 10, 2014

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